Paf1 and Ctr9, core components of the PAF1 complex, maintain low levels of telomeric repeat containing RNA

The conserved PAF1 complex (Cdc73, Paf1, Ctr9, Leo1 and Rtf1, in yeast), binds RNA pol II, and affects levels of many RNAs. Although PAF1 is a complex, there is evidence that different components perform different functions. In yeast, Cdc73, Paf1 and Ctr9 maintain normal telomerase RNA (TLC1) levels and affect telomere length. Here we report a new connection between the PAF1 complex and telomere biology. We show that Paf1 and Ctr9 maintain low telomere repeat containing RNA (TERRA) levels while Cdc73, Leo1 and Rtf1 have lesser effects. Analysis of double mutants shows that Paf1 and Ctr9 can affect TERRA independently of Sir4, Rat1, and Trf4, previously identified regulators of TERRA. The data suggest that Paf1 and Ctr9 maintain low TERRA levels by affecting both transcription and degradation and that short telomeres in cdc73Δ, paf1Δ and ctr9Δ mutants do not induce TERRA. These data establish the PAF1 complex as a new regulator of TERRA, and are consistent with the model in which Paf1 and Ctr9, the core components of the PAF1 complex, affect transcript levels and cell fitness by numerous mechanisms.